<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8">
		<title>Document</title>
		<style>
			* {
				padding: 0;
				margin: 0;
			}

			.nav {
				color: white; q
				height: 90px;
				width: 100%;
				/*background-color: #3d3d3d;*/
				background-color: rgba(0, 0, 0, .5);
				position: fixed;
				/* 透明度, 值0-1 */
				/*opacity: .2;*/
			}

			p {
				font-size: 20px;
				text-align: center;
				margin-top: 30px;
			}

			p>a {
				color: white;
				margin: 0 30px;
			}

			.blue {
				width: 900px;
				height: 2000px;
				background-color: blue;
			}


		</style>
	</head>
	<body>

		<div class="nav">
			<p>
				<a href="">HOME</a>
				<a href="">WORK</a>
				<a href="">CONTACT</a>
				<a href="">JOIN US</a>
			</p>
		</div>

		<div class="blue"></div>
		
	</body>
</html>